U.S. patent application number 17/307388 was filed with the patent office on 2022-06-02 for multilayer capacitor.
The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Hye Min BANG, Hai Joon LEE, Jang Yeol LEE, Tae Joon PARK.
Application Number | 20220172898 17/307388 |
Document ID | / |
Family ID | 1000005609722 |
Filed Date | 2022-06-02 |
United States Patent
Application |
20220172898 |
Kind Code |
A1 |
LEE; Jang Yeol ; et
al. |
June 2, 2022 |
MULTILAYER CAPACITOR
Abstract
A multilayer capacitor includes a body including a stack
structure in which a plurality of dielectric layers are stacked and
a plurality of internal electrodes are stacked with the dielectric
layers interposed therebetween, external electrodes formed on an
external surface of the body to be connected to the internal
electrodes, and including a first electrode layer covering a first
surface of the body to which the internal electrodes are exposed,
and a second electrode layer covering the first electrode layer, a
first metal oxide layer disposed between the first and second
electrode layers and having a discontinuous region, and a second
metal oxide layer covering at least a portion of a surface of the
body on which the external electrodes are not disposed and having a
multilayer structure.
Inventors: |
LEE; Jang Yeol; (Suwon-si,
KR) ; BANG; Hye Min; (Suwon-si, KR) ; PARK;
Tae Joon; (Suwon-si, KR) ; LEE; Hai Joon;
(Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Family ID: |
1000005609722 |
Appl. No.: |
17/307388 |
Filed: |
May 4, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01G 4/248 20130101;
H01G 4/30 20130101; H01G 4/008 20130101; H01G 4/012 20130101 |
International
Class: |
H01G 4/30 20060101
H01G004/30; H01G 4/248 20060101 H01G004/248; H01G 4/012 20060101
H01G004/012; H01G 4/008 20060101 H01G004/008 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2020 |
KR |
10-2020-0162565 |
Claims
1. A multilayer capacitor comprising: a body including a stack
structure in which a plurality of dielectric layers are stacked and
a plurality of internal electrodes are stacked with the dielectric
layers interposed therebetween; external electrodes formed on an
external surface of the body to be connected to the internal
electrodes, and including a first electrode layer covering a first
surface of the body to which the internal electrodes are exposed,
and a second electrode layer covering the first electrode layer; a
first metal oxide layer disposed between the first and second
electrode layers and having a discontinuous region; and a second
metal oxide layer covering at least a portion of a surface of the
body on which the external electrodes are not disposed and having a
multilayer structure.
2. The multilayer capacity of claim 1, wherein the first and second
metal oxide layers are in contact with each other.
3. The multilayer capacity of claim 2, wherein a boundary between
the first and second metal oxide layers is located at an end
portion of the second electrode layer.
4. The multilayer capacity of claim 1, wherein the first and second
metal oxide layers include the same metal oxide component.
5. The multilayer capacity of claim 1, wherein the second metal
oxide layer covers a second surface of the body, perpendicular to a
stacking direction of the plurality of internal electrodes and a
third surface of the body, perpendicular to the first and second
surfaces.
6. The multilayer capacity of claim 5, wherein the second metal
oxide layer covers the entirety of the second surface and the third
surface of the body on which the external electrodes are not
disposed and having a multilayer structure.
7. The multilayer capacity of claim 1, wherein at least a portion
of the discontinuous region of the first metal oxide layer is
filled with at least one of the first and second electrode
layers.
8. The multilayer capacity of claim 1, wherein the first and second
electrode layers include the same material.
9. The multilayer capacity of claim 1, wherein the first and second
electrode layers include at least one of copper (Cu) or nickel
(Ni).
10. The multilayer capacity of claim 1, wherein the first and
second electrode layers include a metal oxide, which is also
included in the first metal oxide layer.
11. The multilayer capacity of claim 1, wherein the first metal
oxide layer further includes a glass component.
12. The multilayer capacity of claim 1, wherein the multilayer
structure of the second metal oxide layer includes a first layer
disposed on the surface of the body on which the external
electrodes are not disposed and having a multilayer structure, and
a second layer disposed on the first layer, wherein a component
included in the first layer is different from a component included
in the second layer.
13. The multilayer capacity of claim 12, wherein the first layer
and the second layer are repeatedly stacked alternately at least
two times.
14. The multilayer capacity of claim 13, wherein the first layer is
divided into a plurality of regions by a first gap formed between
the divided regions, and the second layer is divided into a
plurality of regions by a second gap formed between the divided
regions.
15. The multilayer capacity of claim 14, wherein the first gap and
the second gap are disposed so as not to overlap in a thickness
direction of the first layer and the second layer in at least some
regions of the stack structure.
16. The multilayer capacity of claim 1, wherein the first metal
oxide layer has a multilayer structure.
17. The multilayer capacity of claim 1, wherein a surface of the
first metal oxide layer has a random shape.
18. The multilayer capacity of claim 1, wherein the surface of the
body includes a groove, and the second metal oxide layer fills the
groove.
19. The multilayer capacity of claim 1, wherein the external
electrodes further include an additional electrode layer covering
the second electrode layer, and an end portion of the additional
electrode layer covers the second metal oxide layer.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims benefit of priority to Korean Patent
Application No. 10-2020-0162565 filed on Nov. 27, 2020 in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND
1. Field
[0002] The present disclosure relates to a multilayer
capacitor.
2. Description of Related Art
[0003] A capacitor is an element capable of storing electricity,
and generally uses a principle in which electricity is accumulated
in each electrode when a voltage is applied by opposing two
electrodes. When a direct current (DC) voltage is applied to the
capacitor, a current flows in the capacitor while the electricity
is accumulated, but when the accumulation of the electricity is
completed, the current does not flow in the capacitor. Meanwhile,
when an alternating current (AC) voltage is applied to the
capacitor, an alternating current flows in the capacitor while
polarities of the electrodes are alternated.
[0004] Such a capacitor may be classified as one of several kinds
of capacitors such as an aluminum electrolytic capacitor in which
electrodes are formed of aluminum and a thin oxide layer is
disposed between the electrodes formed of aluminum, a tantalum
capacitor in which tantalum is used as an electrode material, a
ceramic capacitor in which a dielectric material having a high
dielectric constant such as a barium titanate is used between
electrodes, a multilayer ceramic capacitor (MLCC) in which a
ceramic having a high dielectric constant is used in a multilayer
structure as a dielectric material provided between electrodes, a
film capacitor in which a polystyrene film is used as a dielectric
material provided between electrodes, and the like, depending on a
kind of insulator provided between electrodes.
[0005] Thereamong, the multilayer ceramic capacitor has been
recently used mainly in various fields such as a high frequency
circuit, and the like, since it has excellent temperature
characteristics and frequency characteristics and may be
implemented at a small size. In recent years, attempts to implement
a smaller multilayer ceramic capacitor continue, and to this end,
dielectric layers and internal electrodes are formed thinly.
[0006] In recent years, in the field of multilayer capacitor, many
attempts have been made to improve moisture resistance reliability
by reducing defects caused by penetration of moisture or plating
solutions. As one method, when a cover layer of a capacitor body or
an external electrode is formed to be thick, there may be a problem
that a size of a component increases and a capacitance decreases at
the same size.
SUMMARY
[0007] An aspect of the present disclosure may provide a multilayer
capacitor having improved moisture resistance reliability.
[0008] According to an aspect of the present disclosure, a
multilayer capacitor may include a body having a stack structure in
which a plurality of dielectric layers are stacked and a plurality
of internal electrodes are stacked with the dielectric layers
interposed therebetween; external electrodes formed on an external
surface of the body to be connected to the internal electrodes, and
including a first electrode layer covering a first surface of the
body to which the internal electrodes are exposed, and a second
electrode layer covering the first electrode layer; a first metal
oxide layer disposed between the first and second electrode layers
and having a discontinuous region; and a second metal oxide layer
covering at least a portion of a surface of the body on which the
external electrodes are not disposed and having a multilayer
structure.
[0009] The first and second metal oxide layers may be in contact
with each other.
[0010] A boundary between the first and second metal oxide layers
may be located at an end portion of the second electrode layer.
[0011] The first and second metal oxide layers may include the same
metal oxide component.
[0012] The second metal oxide layer may cover a second surface of
the body, perpendicular to a stacking direction of the plurality of
internal electrodes and a third surface of the body, perpendicular
to the first and second surfaces of the body.
[0013] The second metal oxide layer may cover the entirety of the
second surface and the third surface of the body.
[0014] At least a portion of the discontinuous region of the first
metal oxide layer may be filled with at least one of the first and
second electrode layers.
[0015] The first and second electrode layers may include the same
material.
[0016] The first and second electrode layers may include at least
one of copper (Cu) or nickel (Ni).
[0017] The first and second electrode layers may include a metal
oxide formed of the same component as that included in the first
metal oxide layer.
[0018] The first metal oxide layer may further include a glass
component.
[0019] The multilayer structure of the second metal oxide layer may
include a stack structure of a first layer and a second layer of
different components.
[0020] The first layer and the second layer may be repeatedly
stacked alternately at least two times.
[0021] The first layer may be divided into a plurality of regions
by a first gap formed between the divided regions, and the second
layer may be divided into a plurality of regions by a second gap
formed between the divided regions.
[0022] The first gap and the second gap may be disposed so as not
to overlap in a thickness direction of the first layer and the
second layer in at least some regions of the stack structure.
[0023] The first metal oxide layer may have a multilayer
structure.
[0024] A surface of the first metal oxide layer may have a random
shape.
[0025] A groove may be formed on the surface of the body, and the
second metal oxide layer may fill the groove.
[0026] The external electrodes may further include an additional
electrode layer covering the second electrode layer, and an end
portion of the additional electrode layer may cover the second
metal oxide layer.
BRIEF DESCRIPTION OF DRAWINGS
[0027] The above and other aspects, features and other advantages
of the present disclosure will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0028] FIG. 1 is a schematic perspective view illustrating an
appearance of a multilayer capacitor according to an exemplary
embodiment in the present disclosure;
[0029] FIG. 2 is a cross-sectional view taken along line I-I' of
the multilayer capacitor of FIG. 1;
[0030] FIG. 3 is a cross-sectional view taken along line II-II' of
the multilayer capacitor of FIG. 1; and
[0031] FIG. 4 is an enlarged view of a partial region A of FIG.
2.
[0032] FIG. 5 is an enlarged view of a partial region B of FIG.
2.
[0033] FIG. 6 is an enlarged view of a partial region B of FIG. 2
illustrating another exemplary embodiment of the present
disclosure;
[0034] FIG. 7 is an enlarged view of a partial region B of FIG. 2
illustrating another exemplary embodiment of the second metal oxide
layer of the present disclosure;
[0035] FIG. 8 is an enlarged view of a partial region B of FIG. 2
illustrating another exemplary embodiment of the second metal oxide
layer of the present disclosure;
[0036] FIG. 9 is an enlarged view of a partial region A of FIG.
2.
DETAILED DESCRIPTION
[0037] Hereinafter, exemplary embodiments in the present disclosure
will be described in detail with reference to the accompanying
drawings. However, the exemplary embodiments in the present
disclosure may be modified in many different forms and the scope of
the present disclosure is not limited to the exemplary embodiments
described below. In addition, the exemplary embodiments in the
present disclosure are provided in order to more completely explain
the present disclosure to a person skilled in the art. Therefore,
the shapes and sizes of elements in the drawings may be exaggerated
for clearer description, and elements indicated by the same
reference numerals in the drawings are the same elements.
[0038] In addition, in the drawings, portions unrelated to the
description will be omitted in order to clearly describe the
present disclosure, thicknesses of several layers and regions are
exaggerated for clarity, and components having the same functions
within the scope of the same idea will be denoted by the same
reference numerals. Further, throughout the specification, when a
certain portion "includes" a certain component, it means that other
components may be further included rather than excluding other
components unless otherwise stated.
[0039] FIG. 1 is a schematic perspective view illustrating an
appearance of a multilayer capacitor according to an exemplary
embodiment in the present disclosure. FIGS. 2 and 3 are
cross-sectional views taken along lines I-I' and II-II' of the
multilayer capacitor of FIG. 1, respectively. In addition, FIGS. 4
through 9 are enlarged views of a partial region of FIG. 2.
[0040] Referring to FIGS. 1 through 4, a multilayer capacitor 100
according to an exemplary embodiment in the present disclosure may
include a body 110 including dielectric layers 111 and a plurality
of internal electrodes 121 and 122 stacked with each of the
dielectric layers 111 interposed therebetween, external electrodes
131 and 132, and first and second metal oxide layers 151 and 152.
Here, the first and second metal oxide layers 151 and 152 may
prevent intrusion of moisture or plating solution from the outside.
The first metal oxide layer 151 may have a discontinuous region D,
and the second metal oxide layer 152 may have a multilayer
structure.
[0041] The body 110 may include a plurality of dielectric layers
111, and may be obtained by stacking and then sintering, for
example, a plurality of green sheets. The plurality of dielectric
layers 111 may have a form in which they are integrated with one
another by such a sintering process. In addition, as illustrated in
FIG. 1, the body 110 may have a rectangular parallelepiped shape.
The dielectric layer 111 included in the body 110 may include a
ceramic material having a high dielectric constant, for example, a
BT-based ceramic material, that is, barium titanate
(BaTiO.sub.3)-based ceramic material, but may include other
materials known in the related art as long as a sufficient
capacitance may be obtained. The dielectric layer 111 may further
include additives, organic solvents, plasticizers, binders,
dispersants, and the like, if necessary, together with the ceramic
material, which is a main component. Here, the additives may be
added in a metal oxide form in a manufacturing process. Examples of
such a metal oxide additive may include at least one of MnO.sub.2,
Dy.sub.2O.sub.3, BaO, MgO, Al.sub.2O.sub.3, SiO.sub.2,
Cr.sub.2O.sub.3, or CaCO.sub.3.
[0042] Each of the plurality of internal electrodes 121 and 122 may
be obtained by printing and then sintering a paste including a
conductive metal at a predetermined thickness on one surface of the
ceramic green sheet. In this case, the plurality of internal
electrodes may include first and second internal electrodes 121 and
122 exposed in directions of the body 110 opposing each other (Z
direction based on the drawing), and a surface of the body 110 to
which the first and second internal electrodes 121 and 122 are
exposed will be defined as a first surface S1. The first and second
internal electrodes 121 and 122 may be connected to different
external electrodes 131 and 132, respectively, to have different
polarities when the multilayer capacitor is driven, and may be
electrically separated from each other by each of the dielectric
layers 111 disposed therebetween. However, according to another
exemplary embodiment, the number of external electrodes 131 and 132
or a connection manner of the internal electrodes 121 and 122 may
be changed. An example of a main material constituting the internal
electrodes 121 and 122 may include copper (Cu), nickel (Ni), silver
(Ag), palladium (Pd), or the like, or alloys thereof.
[0043] The external electrodes 131 and 132 may include first and
second external electrodes 131 and 132 formed on external surfaces
of the body 110 and electrically connected to the first and second
internal electrodes 121 and 122, respectively. Each of the external
electrodes 131 and 132 may include a first electrode layer 141 and
a second electrode layer 142, and may further include an additional
electrode layer 143.
[0044] The first electrode layer 141 may be disposed on the first
surface S1 of the body 110. Here, the first surface S1 may
correspond to the surface to which the internal electrodes 121 and
122 are exposed. The first electrode layer 141 may be connected to
the internal electrodes 121 and 122 and may be formed of a
conductive material such as copper (Cu), nickel (Ni), or an alloy
thereof. The first electrode layer 141 may be formed by
transferring, printing, or dipping a conductive paste on the first
surface S1 of the body 110. In this case, the first electrode layer
141 may be formed on all of a second surface S2, perpendicular to a
stacking direction (X direction) of the internal electrodes 121 and
122, and a third surface S3, perpendicular to the first and second
surfaces S1 and S2, in addition to the first surface S1 of the body
110. However, depending on the exemplary embodiment, the first
electrode layer 141 may also be formed only on the first surface S1
of the body 110. The second electrode layer 142 may cover the first
electrode layer 141 and may be formed of a conductive material such
as nickel (Ni), copper (Cu), or an alloy thereof. In this case, the
second electrode layer 142 may include the same material as the
first electrode layer 141. The second electrode layer 142 may be
formed by transferring, printing, or dipping a conductive paste to
cover a first metal oxide layer 151. When the above-described
method is used, the first and second electrode layers 141 and 142
may be implemented in the form of sintered electrodes obtained by
sintering the conductive paste.
[0045] The first metal oxide layer 151 may be disposed between the
first and second electrode layers 141 and 142 and may have a
discontinuous region D as illustrated in FIG. 4. The first metal
oxide layer 151 may effectively block a plating solution from
penetrating into the body 110 through the electrode layers 141 and
142. To this end, in the present exemplary embodiment, by
implementing the first metal oxide layer 151 with a metal oxide
that may be coated relatively thinly and uniformly, the size of the
external electrodes 131 and 132 may be kept small, while improving
moisture resistance blocking characteristics. In consideration of
this function, a metal oxide component included in the first metal
oxide layer 151 may include, for example, an oxide of silicon (Si),
aluminum (Al), zirconium (Zr), lithium (Li), or hafnium (Hf).
[0046] The first metal oxide layer 151 may include the
discontinuous region D. Here, at least some of the discontinuous
region D may be filled with at least one of the first and second
electrode layers 141 and 142 so that the first and second electrode
layers 141 and 142 may be connected to each other. Electrical
connection paths between the first and second electrode layers 141
and 142 may be formed by the discontinuous region D. The
discontinuous region D of the first metal oxide layer 151 may be
formed as the metal oxide component of the first metal oxide layer
151 is melted and a portion of the first metal oxide layer 151 is
separated in a process of sintering the first and second electrode
layers 141 and 142. Accordingly, as illustrated in FIG. 9, a
surface of the first metal oxide layer 151 may also be formed in a
random shape. The first metal oxide layer 151 may be seen to
maintain a layer shape as a whole when viewed from a cross section,
and a plurality of regions divided by the discontinuous region D
may exist in the form of an island. In addition, the first and
second electrode layers 141 and 142 may include a metal oxide "O"
having the same component as that included in the first metal oxide
layer 151. In this case, the metal oxide of the first metal oxide
layer 151 or the metal oxide O present in the first and second
electrode layers 141 and 142 may be melted together with glass
components of the first and second electrode layers 141 and 142 and
may react therewith. Accordingly, the first metal oxide layer 151
does not include only the metal oxide, but may also partially
include the glass component. In addition, the first metal oxide
layer 151 may have a multilayer structure as indicated by a dotted
line in FIG. 4. This may be obtained by simultaneously forming the
first and second metal oxide layers 151 and 152 in the multilayer
structure, as will be described later. However, since a portion of
the first metal oxide layer 151 may be lost during the sintering
process, the first metal oxide layer 151 does not have a distinct
multilayer structure as compared to the second metal oxide layer
152.
[0047] The second metal oxide layer 152 may cover at least a
portion of a surface of the body 110 on which the external
electrodes 131 and 132 are not disposed. In the present exemplary
embodiment, the second metal oxide layer 152 may cover the second
surface S2 and the third surface S3 of the body 110. In addition,
the second metal oxide layer 152 may cover the entirety of the
second surface S2 and the third surface S3. Since the surface of
the body 110 is not exposed by such an entire surface cover
structure, the body 110 may be effectively blocked from external
moisture. In addition, the second metal oxide layer 152 may include
a multilayer structure, for example, a stack structure of a first
layer 161 and a second layer 162 on each other as illustrated in
FIG. 5, from which a moisture resistance blocking performance may
be further improved. In this case, the first layer 161 and the
second layer 162 may include different components. For example, the
first layer 161 may include Al.sub.2O.sub.3, and the second layer
162 may include HfO.sub.2. In addition, as illustrated in FIG. 6,
the first layer 161 and the second layer 162 may be repeatedly
stacked alternately two or more times. In addition, as illustrated
in FIG. 7, in the second metal oxide layer 152, the first layer 161
may be divided into a plurality of regions by a first gap G1 formed
between the divided regions, and similarly, the second layer 162
may be divided into a plurality of regions by a second gap G2
formed between the divided regions. In this case, positions of the
first and second gaps G1 and G2 may be adjusted for moisture
resistance blocking performance. Specifically, in at least some
regions of the stack structure of the second metal oxide layer 152,
the first gap G1 and the second gap G2 may be disposed so as not to
overlap in a thickness direction (vertical direction based on the
drawing) of the first layer 161 and the second layer 162.
[0048] As illustrated in FIG. 2, the first and second metal oxide
layers 151 and 152 may be in contact with each other. In this case,
a boundary between the first and second metal oxide layers 151 and
152 may be located at an end portion of the second electrode layer
142. Such a connection method of the first and second metal oxide
layers 151 and 152 may be obtained, for example, by entirely
forming a metal oxide film of a multilayer structure on the
surfaces of the first electrode layer 141 and the body 110 after
the first electrode layer 141 is formed. The first and second metal
oxide layers 151 and 152 may include the same metal oxide
component. As described in the example above, the second metal
oxide layer 152 may also include, for example, an oxide of silicon
(Si), aluminum (Al), zirconium (Zr), lithium (Li), or hafnium (Hf).
As described above, the second metal oxide layer 152 may be formed
together with the first metal oxide layer 151 rather than formed in
a final step after forming all of the external electrodes 131 and
132. In this case, an end portion of the additional electrode
layers 143 and 145 in the external electrodes 131 and 132 may cover
the second metal oxide layer 152.
[0049] The second metal oxide layer 152 may be thicker than the
first metal oxide layer 151 (t2>t1). This is because a portion
of the first metal oxide layer 151 may be partially lost in the
process of sintering the external electrodes 131 and 132, as
described above. Meanwhile, considering that the first metal oxide
layer 151 has the random shape, the thickness of the first metal
oxide layer 151 may be defined as a maximum thickness in the
corresponding region. The second metal oxide layer 152 may also be
defined as a maximum thickness. However, since the second metal
oxide layer 152 has a relatively uniform thickness compared to the
first metal oxide layer 151, the second metal oxide layer 152 may
be defined as an average thickness. A method of measurement of the
thickness of the first and second metal oxide layers includes
methods, which is appreciated by the one skilled in the art.
[0050] Referring to FIG. 8, the second metal oxide layer 152 may
fill a groove formed on the surface of the body 110. In this case,
the second metal oxide layer 152 may be formed along a surface of
the groove, that is, to follow the surface of the groove. The
groove on the surface of the body 110 may be a region where defects
of the body 110 exist, and may be a path through which moisture or
plating solution easily penetrates. The moisture resistance
reliability may be further improved by filling the grooves on the
surface of the body 110 with the second metal oxide layer 152 as in
the present exemplary embodiment.
[0051] Referring to FIG. 2 again, the remaining configurations of
the external electrodes 131 and 132 will be described. Each of the
external electrodes 131 and 132 may include an additional electrode
layers 143 and 145 covering the second electrode layer 142. The
additional electrode layers 143 and 145 may be a plating layer, and
may be implemented in a multilayer structure including nickel (Ni),
tin (Sn), or the like. As described above, when the plating layer
is formed, penetration of the plating solution into the body 110 by
the first and second metal oxide layers 151 and 152 may be
effectively blocked. The additional electrode layer 143 may include
a conductive resin electrode in which a conductive material and a
resin are mixed in addition to the plating layer. In this case, the
conductive resin electrode may be disposed on the plating layer and
the second electrode layer 142.
[0052] As set forth above, according to the exemplary embodiments
in the present disclosure, the moisture resistance reliability of
the multilayer capacitor may be improved.
[0053] While exemplary embodiments have been shown and described
above, it will be apparent to those skilled in the art that
modifications and variations could be made without departing from
the scope of the present invention as defined by the appended
claims.
* * * * *